| /* Copyright (C) 2001-2014 Free Software Foundation, Inc. |
| This file is part of the GNU C Library. |
| Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com). |
| |
| The GNU C Library is free software; you can redistribute it and/or |
| modify it under the terms of the GNU Lesser General Public |
| License as published by the Free Software Foundation; either |
| version 2.1 of the License, or (at your option) any later version. |
| |
| The GNU C Library is distributed in the hope that it will be useful, |
| but WITHOUT ANY WARRANTY; without even the implied warranty of |
| MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU |
| Lesser General Public License for more details. |
| |
| You should have received a copy of the GNU Lesser General Public |
| License along with the GNU C Library; if not, see |
| <http://www.gnu.org/licenses/>. */ |
| |
| #include <libintl.h> |
| #include <stdarg.h> |
| #include <stdio.h> |
| #include <stdlib.h> |
| #include <ucontext.h> |
| |
| /* This implementation can handle any ARGC value but only |
| normal integer type parameters. Parameters of type float, |
| double, complex and structure with sizes 0, 2, 4 or 8 |
| won't work. |
| makecontext sets up a stack and the registers for the |
| user context. The stack looks like this: |
| size offset |
| %r15 -> +-----------------------+ |
| 8 | back chain (zero) | 0 |
| 8 | reserved | 8 |
| 144 | save area for (*func) | 16 |
| +-----------------------+ |
| n | overflow parameters | 160 |
| +-----------------------+ |
| The registers are set up like this: |
| %r2-%r6: parameters 1 to 5 |
| %r7 : (*func) pointer |
| %r8 : uc_link from ucontext structure |
| %r9 : address of setcontext |
| %r14 : return address to uc_link trampoline |
| %r15 : stack pointer. |
| |
| The trampoline looks like this: |
| basr %r14,%r7 |
| lgr %r2,%r8 |
| br %r9. */ |
| |
| void |
| __makecontext (ucontext_t *ucp, void (*func) (void), int argc, ...) |
| { |
| extern void __makecontext_ret (void); |
| unsigned long int *sp; |
| va_list ap; |
| |
| sp = (unsigned long int *) (((unsigned long int) ucp->uc_stack.ss_sp |
| + ucp->uc_stack.ss_size) & -8L); |
| |
| /* Set the return address to trampoline. */ |
| ucp->uc_mcontext.gregs[14] = (long int) __makecontext_ret; |
| |
| /* Set register parameters. */ |
| va_start (ap, argc); |
| for (int i = 0; i < argc && i < 5; ++i) |
| ucp->uc_mcontext.gregs[2 + i] = va_arg (ap, long int); |
| |
| /* The remaining arguments go to the overflow area. */ |
| if (argc > 5) |
| { |
| sp -= argc - 5; |
| for (int i = 5; i < argc; ++i) |
| sp[i - 5] = va_arg (ap, long int); |
| } |
| va_end (ap); |
| |
| /* Make room for the save area and set the backchain. */ |
| sp -= 20; |
| *sp = 0; |
| |
| /* Pass (*func) to __makecontext_ret in %r7. */ |
| ucp->uc_mcontext.gregs[7] = (long int) func; |
| |
| /* Pass ucp->uc_link to __makecontext_ret in %r8. */ |
| ucp->uc_mcontext.gregs[8] = (long int) ucp->uc_link; |
| |
| /* Pass address of setcontext in %r9. */ |
| ucp->uc_mcontext.gregs[9] = (long int) &setcontext; |
| |
| /* Set stack pointer. */ |
| ucp->uc_mcontext.gregs[15] = (long int) sp; |
| } |
| |
| weak_alias (__makecontext, makecontext) |